1. Field of the Invention
This invention relates to an on-line method for determining the reliability of an electric power system. It relates more specifically to a method in which data from the power system, including data representing generated energy and load amount, and system connecting status, are inputted, for calculating voltage, frequency and power flow of the power system, and for determining reliability of the power system to indicate faults or to control system operation.
2. Description of the Prior Art
In order to determine reliability of a power system, the power flow must be calculated. However, the calculation includes many complicated operational processes, such as a process for generating and executing an LU decomposition of the Jacobian so that the load of a computer becomes very large. In the prior art, therefore, even if data of the power system are provided via on-line operation, the required processes to the data cannot be carried out at a fast enough speed to suitably execute processes regarding fault indication and system operation.
FIG. 1 shows a flow chart of an algorithm for power flow calculation in the prior art. First, data, including data representing generated power and load amount and system connecting status, are inputted from the power system (process 1). Using the inputted data, a preparatory process for power flow calculation, for example, a process for generating admittance matrix or process for converting data into which is adapted for the flow calculation, is carried out (process 2). A Jacobian is then generated (process 3) and a process is initiated to provide LU decomposition of the Jacobian (processs 4) to obtain data required for convergence calculation of the flow. Calculations of the power flow and its convergence calculation are performed in process 5. Using the result of the convergence calculation, a post process (process 6), for example, a process for obtaining the output value of bus line voltage or power flow in lines of the system, is carried out. Finally, reliability of the power system is determined (process 7) using the bus line voltage and power flow calculated in process 6 to complete one cycle and the further process returns to step 1.
According to such a process cycle, formation and LU decomposition of the Jacobian requiring much processing time must be executed in every cycle so that it is difficult to indicate a fault or to control system operation at any time, and to use present data from the power system to execute the real-time process in a limited time. The lower the processing speed becomes, the lower the decision accuracy becomes.